For new managers I think the most powerful things to do are:
1. Get to know your people. That's the only way to get a good feel for their strengths and motivations.
2. Show interest in developing your people. This tends to be motivating to them and helps them improve their skills. But don't just focus on formal training. A lot of the best learning (including leadership learning) comes from challenging and varied assignments that make the employee stretch and give them greater perspective.
3. Acknowledge that you don't have all the answers. A lot of new managers are too insecure to admit that they don't know it all. (I was that way in my first management job.) That just makes them look foolish to their staff. Most employees love to feel that their opinions and knowledge are valued. Show humility and ask for their help.
From what I have seen, one of the most difficult things for inexperienced managers is dealing with conflict. It takes backbone to deal with under performers, protect your staff from abuse, or speak truth to power--but doing so is absolutely critical. The good news is that this can be learned... and it is self-reinforcing because when you actually deal with problems they go away.